Sibling invalidation sets

Source/core/css/invalidation/InvalidationSet.cpp

Index: Source/core/css/invalidation/InvalidationSet.cpp
diff --git a/Source/core/css/invalidation/InvalidationSet.cpp b/Source/core/css/invalidation/InvalidationSet.cpp
index 617e9b974e5a946d7dfabd2307c2c5c4e39b0b1e..12378db45620517b96cf59ac8c01f7c7d1f2a6aa 100644
--- a/Source/core/css/invalidation/InvalidationSet.cpp
+++ b/Source/core/css/invalidation/InvalidationSet.cpp
@@ -52,7 +52,9 @@ void InvalidationSet::cacheTracingFlag()
 }
 
 InvalidationSet::InvalidationSet()
-    : m_allDescendantsMightBeInvalid(false)
+    : m_maxDirectAdjacentSelectors(1)
+    , m_appliesDirectly(false)
+    , m_allDescendantsMightBeInvalid(false)
     , m_customPseudoInvalid(false)
     , m_treeBoundaryCrossing(false)
     , m_insertionPointCrossing(false)
@@ -98,6 +100,14 @@ bool InvalidationSet::invalidatesElement(Element& element) const
 
 void InvalidationSet::combine(const InvalidationSet& other)
 {
+    m_maxDirectAdjacentSelectors = std::max(m_maxDirectAdjacentSelectors, other.m_maxDirectAdjacentSelectors);
+
+    if (other.descendants())
+        ensureDescendantInvalidationSet().combine(*other.descendants());
+
+    if (other.appliesDirectly())
+        setAppliesDirectly();
+
     // No longer bother combining data structures, since the whole subtree is deemed invalid.
     if (wholeSubtreeInvalid())
         return;
@@ -165,6 +175,14 @@ WillBeHeapHashSet<AtomicString>& InvalidationSet::ensureAttributeSet()
     return *m_attributes;
 }
 
+InvalidationSet& InvalidationSet::ensureDescendantInvalidationSet()
+{
+    if (!m_descendantInvalidationSet)
+        m_descendantInvalidationSet = InvalidationSet::create();
+
+    return *m_descendantInvalidationSet;
+}
+
 void InvalidationSet::addClass(const AtomicString& className)
 {
     if (wholeSubtreeInvalid())
@@ -215,6 +233,7 @@ DEFINE_TRACE(InvalidationSet)
     visitor->trace(m_ids);
     visitor->trace(m_tagNames);
     visitor->trace(m_attributes);
+    visitor->trace(m_descendantInvalidationSet);
 #endif
 }